Disc cartridge having annular shaped mating projections

ABSTRACT

A disc cartridge accommodating an optical disc in a cartridge body. The disc cartridge includes a cartridge body formed by mating and joining upper and lower halves mated together. A plurality of fusing portions for mating and fusing the upper and lower halves are provided at positions corresponding to recess portions for accommodating an optical disc. Each fusing portion is provided with a mating projection formed at one of the upper and lower halves and a mating projection formed at the other of the upper and lower halves. A plurality of mating projections formed at either half comprise mating projections having projections for fusing annularly and continuously formed over the entire circumference of the end surfaces to be mated to the mating projections of the other half and mating projections having projections for fusing formed in the form of an arc in one part of the end surfaces.

TECHNICAL FIELD

The present invention relates to a disc cartridge accommodating adisk-like recording medium such as an optical disc on which a datasignal is recorded, more particularly relates to a disc cartridge inwhich a disk-like recording medium is accommodated in a cartridge bodyformed by placing together and connecting a pair of upper and lowerhalves formed by shaping a plastic material.

BACKGROUND ART

Conventionally, a disc cartridge accommodating a disk-like recordingmedium such as an optical disc on which a data signal is recorded isconstituted by being provided with a cartridge body formed by placingtogether and connecting a pair of upper and lower halves formed byshaping a plastic material such as an ABS resin and by accommodating thedisk-like recording medium in this cartridge body so that it can rotate.The disc cartridge is mounted in a recording and/or reproducingapparatus in a state with the disk-like recording medium accommodatedtherein as it is. The disk-like recording medium accommodated in thecartridge body is chacked on a disc table constituting part of the discrotating mechanism with a center portion arranged on the recordingand/or reproducing apparatus side and is operated to rotate togetherwith the disc table.

In a disc cartridge using an optical disc as the disk-like recordingmedium, when the optical disc accommodated in the cartridge body ischacked on the disc table and rotated together with the disc table, thesignal recording portion formed on the main surface is scanned by alight beam emitted from an optical pick-up so as to reproduce therecorded data signal.

Further, when recording a data signal, an external magnetic fieldsubjected to magnetic field modulation in accordance with the datasignal to be recorded from a magnetic head serving as an externalmagnetic field generation means is applied to this signal recordingportion in a state where the light beam emitted from the optical pick-upis irradiated to the signal recording portion of the optical disc so asto record a predetermined data signal.

The optical disc accommodated in the disc cartridge is generallyconstituted by a disc substrate formed by shaping a transparent plasticmaterial and a hub for magnetic clamping which is formed by a magneticplate such as a metal plate and installed in a center hole provided atthe center portion of this disc substrate. On the main surface of thisdisc is provided a signal recording portion on which recording tracks inwhich the data signal is recorded are formed in concentric circlesaround the center hole.

In the lower half of the cartridge body is provided a central openingwhich is positioned at the center and into which a circular disc tableconstituting part of the disc rotating mechanism intrudes is inserted.This central opening specifically makes the hub for the magnet clampingattached to the disc substrate so as to cover the center hole faceoutward.

Further, in the upper half and lower half of the cartridge body,openings for recording and/or reproduction which make one part of a datasignal recording portion provided on the main surface of the opticaldisc face outward over the inner and outer circumferences and to whichrecording and reproduction means such as an optical pick-up or anexternal magnetic field generation means arranged on the recordingand/or reproducing apparatus side face are provided at facing positions.These openings for recording and/or reproduction are positioned at thecenter of the cartridge body in the horizontal direction and areconstituted as rectangular openings covering an area from the front sideto a position close to the central opening. Note that, in a disccartridge accommodating an optical disc used only for reproduction, onlyan opening for reproduction is formed in the lower half side—the upperhalf side is closed.

Further, the disc cartridge has movably attached to it a shutter memberfor closing the opening for recording and/or reproduction to prevent theintrusion of the dust etc. into the cartridge body and, at the sametime, for preventing damage to the optical disc accommodated in thecartridge body in a state when the cartridge is not loaded in therecording and/or reproducing apparatus. This shutter member is movedfrom the position closing the opening for recording and/or reproductionto the opening position by a shutter opening member provided on therecording and/or reproducing apparatus side by the operation of loadingthe disc cartridge in the recording and/or reproducing apparatus.Further, when the disc cartridge is loaded in the recording and/orreproducing apparatus, the disc cartridge bull enters via the centralopening and the optical disc accommodated in the cartridge body ischacked on this disc table.

Note that the upper half and lower half of the cartridge body are formedas generally shallow dish-like rectangular shapes with risingcircumferential walls constituting the circumferential side wall of thecartridge body integrally formed along the circumferential edges.Further, on the inner surfaces at which the upper and lower halves faceeach other, annular walls for forming the portion accommodating therecording medium which are mated with each other to form the discaccommodating portion are formed so as to be inscribed in the risingcircumferential walls. At the same time, mating projections whichconstitute a plurality of fusing portions which are to be mated witheach other and joined are provided. These mating projections arearranged at appropriate positions of the inner surfaces at which theupper half and lower half face each other so that no gap will beproduced between these upper half and lower half when the upper half andthe lower half are mated and joined and so that therefore no dust etc.will intrude into the inside.

Here, explaining the mating projections provided so as to join the upperand lower halves by fusing, these mating projections 101 and 103 areprovided on the surfaces at which the upper half 100 and the lower half102 to be mated and joined to each other and constituting the cartridgebody face each other as shown in FIG. 1 and FIG. 2. These matingprojections 101 and 103 are formed in a cylindrical shape. A projection105 for the fusing of a thickness which becomes narrower toward thefront end is integrally formed on an end surface 104 of the matingprojection 103, provided in the lower half 102, to which an end surface106 of the mating projection 101 provided on the upper half 100 faces.This projection 105 is formed in the shape of a ring over the entirecircumference of the end surface 106 of the mating projection 101.

Note that, the mating projections 101 and 103 are provided in a regionsurrounded by the rising circumferential walls provided on the upper andlower halves 100 and 102 constituting the circumferential walls of thecartridge body and annular walls forming the portion accommodating therecording medium constituting the disc accommodating portion.

The mating projections 101 and 103 are fused together by melting theprojections 105 by application of an ultrasonic wave to the end surfaces104 and 106 which are mated with each other in a state where the upperhalf 100 and the lower half 102 are connected with each other. Namely,by fusing the mating projections 101 and 103, the upper and lower halves100 and 102 are joined with each other to constitute the cartridge body.

Note that in the ultrasonic welding method, when an ultrasonic weldingdevice is driven in a state where the phone for generating theultrasonic wave of the ultrasonic welding device is pressed against themain surface of either of the upper half 100 or the lower half 102acting as the body to be fused and the ultrasonic wave is applied to theupper and lower halves 100 and 102 via the phone, the ultrasonic waveconcentrates at the mated portion, that is, between the end surface 106of the mating projection 101 provided on the upper half 100 side and theprojection 105 formed on the end surface 104 of the mating projection103 provided on the lower half 102 side so ultrasonic vibration isgenerated in this mated portion. The mated portion is hated due to thisultrasonic vibration, whereby the projection 105 is melted to fuse theend surfaces 106 and 104 of the mating projections 101 and 103.

In a disc cartridge connecting the upper and lower halves 100 and 102 byusing the ultrasonic welding method as mentioned above, a plurality ofmating projections 101 and 103 are provided on the upper and lowerhalves 100 and 102 and these mating projections 101 and 103 aresimultaneously fused together. Further, the projection 105 for thefusing formed on the mating projection 103 on the lower half 102 sidefused by the application of the ultrasonic wave is formed as a ringcovering the entire circumference of the end surface 104 of the matingprojection 103. For this reason, there is a case where it becomesdifficult to uniformly fuse all of the plurality of sets of matingprojections 101 and 103.

In order to simultaneously apply the ultrasonic wave to a plurality ofsets of mating projections 101 and 103 to melt the projections105 andperform the ultrasonic welding, the time for applying the ultrasonicwave to the upper and lower halves 100 and 102 becomes long.

Further, in the disc cartridge, to prevent the staining due to theadhesion of dust etc. from being conspicuous, fine pebbling formed inthe main surface on the outside of the upper and lower halves of thecartridge body. Such fine pebbling is smoothed by the contact of thephone of the ultrasonic welding device over a long time. As a result, acontact mark is formed at the portion where the phone comes into contactand the sense of beauty of the outer appearance is degraded.

Further, there also exists a concern that, due to the application of anultrasonic wave over a long time, the optical disc will vibrate in thecartridge body, rubbing will occur between the optical disc and thewalls forming the portion accommodating the recording mediumconstituting the disc accommodating portion, and the optical disc willbe scratched or shaving powder will be generated. When the shavingpowder is generated and adhers to the signal recording portion, therealso exists a concern of occurrence of the omissions in the recordingand/or reproduction of the data signal.

Further, in a disc cartridge accommodating a disk-like recording mediumsuch as an optical disc or magnetic disc, use is made of a disccartridge which may accommodate disk-like recording media of differenttypes but having generally the same size in the cartridge body. Forexample, use is made of a disc cartridge accommodating an optical discor magnetic disc having a diameter of 3.5 inch. In this type of disccartridge, since the size of the disk-like recording media to beaccommodated in the cartridge body is generally made the same, the sizeof the cartridge bodies is generally made the same. In this way, in adisc cartridge accommodating an optical disc or magnetic disc of adiameter of 3.5 inch, it becomes extremely difficult to distinguish thetwo from the outer appearance. For this reason, there also exists aconcern over erroneous loading, for example, erroneously loading a disccartridge accommodating an optical disc of a diameter of 3.5 inches or adisc cartridge accommodating a magnetic disc of a diameter of 3.5 inchin the recording and/or reproducing apparatus.

Further, in a recording and/or reproducing apparatus using a disccartridge accommodating an optical disc as the recording medium and arecording and/or reproducing apparatus using a disc cartridgeaccommodating a magnetic disc as the recording medium, the recordingand/or reproduction means are completely different, so if the cartridgesare erroneously loaded in the apparatuses, there is a concern that notonly will the recording and/or reproduction of the data signal not becarried out, but also the recording and/or reproduction means such asthe optical pick-up or the magnetic head provided on the recordingand/or reproducing apparatus side will be damaged.

Therefore, in the disc cartridge which accommodates disk-like recordingmedia of different types but having generally the same size in thecartridge body, to prevent the disc cartridges from being loaded in anapparatuses other than the suitable recording and/or reproducingapparatuses, a means is provided for preventing erroneous loading. Asthis means for preventing erroneous loading, a means providing a recessor engagement groove in one part of the cartridge body has been known.These recess and engagement grooves for preventing erroneous loadingenable the loading of only the disc cartridge suited to the recordingand/or reproducing apparatus by engagement of one part of the mechanismfor preventing erroneous loading provided on the recording and/orreproducing apparatus side or non-engagement of one part of themechanism for preventing erroneous loading.

In a disc cartridge wherein the type of the disc cartridge is identifiedand the loading of the same to an apparatus other than the suitablerecording and/or reproducing apparatus is inhibited by providing therecess or engagement groove in one part of the cartridge body in thisway, there is a concern that, if the disc cartridge is erroneouslyloaded in the recording and/or reproducing apparatus, the cartridge bodywill be damaged when the mechanism for preventing erroneous loading isengaged with the recess or engagement groove with which it should notoriginally be engaged. Particularly, in a disc cartridge wherein theupper and lower halves are joined by ultrasonic welding, there is aconcern that the upper and lower halves will come apart.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a disc cartridge ableto accommodate disk-like recording media of different types having acommon size which facilitates the identification of the disc cartridgeshaving a generally common shape and can prevent damage to the cartridgebody even in a case where the disc cartridge is loaded in an unsuitablerecording and/or reproducing apparatus.

Another object of the present invention is to provide a disc cartridgewhich enables reliable joining of the upper half and the lower half ofthe cartridge body by using the ultrasonic welding method.

Still another object of the present invention is to provide a disccartridge which enables reliable joining of the upper half and the lowerhalf of the cartridge body while shortening the time of applying theultrasonic wave.

Further another object of the present invention is to provide a disccartridge which enables joining of the upper half and the lower half byusing the ultrasonic welding method without detracting from the outerappearance of the cartridge body.

A disc cartridge according to the present invention proposed so as toachieve the above objects comprises a disk-like recording medium inwhich a data signal is recorded; a cartridge body exhibiting arectangular shape formed by mating and joining a pair of upper and lowerhalves in which rising circumferential walls which mate with each otherto constitute the circumferential side walls are formed at thecircumferential edges and, at the same time, in which walls for formingan accommodating portion which are mated with each other at mating innersurfaces to constitute the recording medium accommodating portion inwhich the disk-like recording medium is accommodated are formed;openings for recording and reproduction which are positioned at a centerof the cartridge body in the horizontal direction and formed in theupper and lower surfaces of the cartridge body over an area from thevicinity of the center of the cartridge body to the front side and makeone part of the signal recording region of the disk-like recordingmedium face outward over the radial direction; a shutter member which isprovided with a shutter portion for opening or closing these openingsand is attached to the cartridge body so that it can move along thefront surface of the cartridge body; a recess portion for preventingerroneous loading formed on the two sides of the cartridge body and onthe lower half side from the front side to midway of the back side; anda plurality of fusing portions for mating and fusing the upper and lowerhalves at the facing surfaces of the upper and lower halves.

Here, each fusing portion for mating and fusing the upper and lowerhalves is provided with a mating projection formed at one of the upperand lower halves and a mating portion formed at the other. The pluralityof mating projections formed at either of the halves each comprises amating projection having a projection for fusing formed annularly andcontinuously over the entire circumference of the end surface for matingto the mating projection of the other half and a mating portions havinga projection for fusing formed at one part of the end surface in theform of an arc.

The mating portion on which the projection for fusing formed in the formof arc is formed is formed on one half with the projection positioned onthe rising circumferential wall side.

Alternatively, each fusing portion for mating and fusing together theupper and lower halves is provided with a mating projection formed atone of the upper and lower halves and a mating portion formed at theother and, for the plurality of mating projections formed at eitherhalf, mating projections in which a plurality of projections for fusingare formed annularly and continuously on the end surface for mating tothe mating projection of the other half are used.

Alternatively, each fusing portion for mating and fusing together theupper and lower halves is provided with a mating projection formed atone of the upper and lower halves and a mating portion formed at theother. As the plurality of mating projections formed at either half, useis made of mating projections each constituted by a mating portionhaving a projection for fusing formed in the form of an arc at one partof the end surface to be mated to the mating projection of the otherhalf and a mating portion formed with a plurality of projections forfusing formed annularly and continuously on the end surface.

Here, a mating portion in which the projection for fusing formed in theform of the arc is formed at one half with the projection positioned onthe rising circumferential wall side.

Further, at least one fusing portion is provided positioned at the twosides of the cartridge body at which the recess portions for preventingthe erroneous loading are formed. By providing the fusing portionsconnecting the upper and lower halves positioned at the two sides atwhich the recess portions for preventing the erroneous loading areformed, the portions in which the recess portions are formed are tightlyconnected.

In the disc cartridge according to the present invention, projectionsare formed on the two sides of the portion for movement of the shuttermember formed on front side of the cartridge body over the range ofmovement in which the shutter member opens or closes the opening and atleast one fusing portion for mating and fusing the upper and lowerhalves is provided in the region of these projections.

Further, a spring biasing the shutter member in a direction closing theopening is arranged in the region surrounded by the circumferential sidewall of one corner of the front side of the cartridge body and the wallsforming the accommodating portion constituting the recording mediumaccommodating portion; and at least one fusing portion for mating andfusing the upper and lower halves is provided in the region surroundedby the circumferential side wall on the other corner of the front sideof the cartridge body and the walls forming the accommodating portionconstituting the recording medium accommodating portion.

Here, the fusing portion provided in the region surrounded by thecircumferential side wall on the other corner of the front side of thecartridge body and the walls forming the accommodating portionconstituting the recording medium accommodating portion is provided witha mating projection formed at one of the upper and lower halves and amating portion formed at the other and is formed with a plurality ofprojections for fusing are annularly and continuously formed on themating end surface of the mating projection cylindrically formed ateither one half.

In the region surrounded by the circumferential side wall on the othercorner of the front side of the cartridge body and the walls forming theaccommodating portion constituting the recording medium accommodatingportion, provision is further made of a fusing portion for mating andfusing the upper and lower halves at a position closer to thecircumferential side wall than the side of the wall forming theaccommodating portion.

In the disc cartridge according to the present invention, a thin portionhaving a thickness less than that of the cartridge body formed by matingof the upper and lower halves is provided at a position on the frontside of the opening formed in the cartridge body and at schematically acenter of the cartridge body in the thickness direction. A fusingportion for mating and fusing the upper and lower halves is provided inthis thin portion.

In the disc cartridge according to the present invention, a positioningmechanism for positioning the mating positions of the upper and lowerhalves in a direction parallel to the direction of movement of theshutter member is provided at one corner on the back side opposite tothe front side at which the shutter member of the cartridge body movesand, at the same time, a positioning mechanism for positioning themating positions of the upper and lower halves in a direction orthogonalto the direction of movement of the shutter member is provided at theother corner on the back side of the cartridge body. Fusing portions formating and fusing the upper and lower halves are provided in thevicinity of the respective positioning mechanisms. The fusing portionsprovided here are each provided with a mating projection formed at oneof the upper and lower halves and a mating projection formed at theother and has a projection for fusing formed in one part of the matingend surface of the mating projection formed at either half. Thisprojection for fusing is formed in schematically an arc shape at onepart of the mating end surface of the cylindrically formed matingprojection.

Here, the positioning mechanism for positioning the mating positions ofthe upper and lower halves in a direction parallel to the direction ofmovement of the shutter member comprises a pair of cylindrical bodiesfor mating with each other provided at the upper and lower halves.Further, the positioning mechanism for positioning the mating positionsof the upper and lower halves in the direction orthogonal to thedirection of movement of the shutter member comprises a cylindricalportion exhibiting a long oval shape having facing surfaces parallel tothe direction of movement of the shutter member and a pair of parallelprojections fitted over the facing surfaces of the cylindrical portion.The cylindrical body and cylindrical portion provided on the lower halfside have formed in them a positioning hole with which a positioning pinon the recording and/or reproducing apparatus side is engaged.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical sectional view showing the configuration of matingprojections formed on the facing inner surfaces so as to join and fix anupper half and a lower half of a cartridge body of a conventional disccartridge.

FIG. 2 is a perspective view showing mating projections provided at theupper and lower halves of the disc cartridge.

FIG. 3 is a perspective view of a disc cartridge according to thepresent invention as seen from the upper side.

FIG. 4 is a perspective view of the above disc cartridge as seen fromthe lower side.

FIG. 5 is a perspective view of disassembled parts of a disc cartridge.

FIG. 6 is a plan view showing the inner surface of the upper half.

FIG. 7 is a plan view showing the inner surface of the lower half.

FIG. 8 is a vertical sectional view showing a fusing portion for joiningthe upper half and the lower half of the cartridge body.

FIG. 9 is a perspective view showing a mating projection constitutingthe fusing portion.

FIG. 10 is a perspective view showing a mating projection provided inthe vicinity of a cylindrical portion provided on the lower half sideconstituting a second positioning mechanism for positioning of themating projections of the upper and lower halves.

FIG. 11 is a perspective view showing the mating projection provided inthe vicinity of a second cylindrical body provided on the lower halfside constituting a first positioning mechanism for positioning of themating projections of the upper and lower halves.

FIG. 12 is a vertical sectional view showing the mating projectionsconstituting another fusing portion provided at the upper and lowerhalves.

FIG. 13 is a perspective view showing the mating projection constitutingthe fusing portion.

FIG. 14 is a plan view of the inner surface showing another example ofthe lower half of the cartridge body.

FIG. 15 is a vertical sectional view showing the mating projectionconstituting a fusing portion provided at the lower half shown in FIG.14.

FIG. 16 is a perspective view showing the mating projection constitutinga fusing portion.

FIG. 17 is a plan view of the inner surface side showing still anotherexample of the lower half of the cartridge body.

FIG. 18 is a vertical sectional view showing a mating projectionconstituting a fusing portion provided at the lower half shown in FIG.17.

FIG. 19 is a perspective view showing a mating projection constituting afusing portion.

FIG. 20 is a vertically sectional view showing another mating projectionconstituting a fusing portion provided at the lower half shown in FIG.17.

FIG. 21 is a perspective view showing a mating projection constituting afusing portion.

FIG. 22 is a plan view showing the inner surface of the lower half atwhich a mating projection constituting a fusing portion for fusingconnection pieces constituting a thin portion of the cartridge body isprovided.

FIG. 23 is a plan view showing the inner surface of the lower halfshowing another example of a fusing portion for fusing the connectionpieces.

FIG. 24 is a plan view showing the inner surface of the lower halfshowing still another example of a fusing portion fusing connectionpieces.

BEST MODE FOR WORKING THE INVENTION

Below, the disc cartridge according to the present invention will beexplained by referring to the drawings.

A disc cartridge 1 according to the present invention is constituted byproviding a cartridge body 20 formed as shown in FIG. 3 and FIG. 4, bymating and joining an upper half 21 and a lower half 22 formed byshaping a plastic material into substantially shallow dish-likerectangles and rotatably accommodating the optical disc 4 in thiscartridge body 20.

The optical disc 4 accommodated in this disc cartridge 1 is formed to adiameter of 3.5 inch and, as shown in FIG. 5, is constituted by a discsubstrate 4 a exhibiting a disk-like shape and a hub 10 for magnetclamping attached so as to be fitted in a center hole 4 b provided atthe center of this disc substrate 4 a.

To fabricate this optical disc 4, as is well known, a stamper isprepared by a mastering process including cutting of the original disk.Then, a plastic material having a light transmitting property such as apolycarbonate resin (PC) or polymethyl methacrylate resin (PMMA) isshaped by a die incorporating this stamper so as to form the discsubstrate 4 a. In this disc substrate 4 a, a center hole 4 b is providedat the center and, at the same time, concavities and convexitiesarranged in concentric circles about the center hole 4 b correspondingto the control signal and the other data signals formed on the surfaceof the stamper are transferred to main surface so as to form the datasignal recording portion on the main surface on which the data signalrecording portion of the disc substrate 4 a is formed, a signalrecording layer comprising a vertical magnetic recording medium etc. isformed. Then the hub 10 is attached to the position corresponding to thecenter hole 4 b of the disc substrate 4 to thereby complete the opticaldisc 4. The hub 10 used here is formed by a magnetic material such as athin metal plate and, as shown in FIG. 5, is constituted by acylindrical fitting 11 having a bottom and an outer circumferentialflange 13 formed flaring out over the entire circumference of the outercircumferential edge of the opening side of this fitting 11. The fitting11 is formed with an outer diameter almost equal to the diameter of thecenter hole 4 b. Further, in the fitting 11, a spindle engagement hole12 with which the spindle shaft projected from the disc table of thedisc rotating mechanism provided on the recording and reproducingapparatus side on which the optical disc 4 is loaded is provided at thecenter portion. The hub 10 is attached by joining the outercircumferential flange 13 to the surface of the disc substrate 4 a byfor example an ultraviolet ray-curable binder in a state where thefitting 11 is fitted in the center hole 4 b. At this time, the hub 10 isattached to the disc substrate 4 a so as to close the center hole 4 b bythe fitting 11.

The upper half 21 and the lower half 22 of the cartridge body 20, asshown in FIG. 5, FIG. 6, and FIG. 7, are formed with risingcircumferential walls 23 and 24 along the circumferential side edges.These rising circumferential walls 23 and 24 constitute thecircumferential side wall 2 of the cartridge body 20 when mating andjoining the upper and lower halves 21 and 22 as shown in FIG. 3 and FIG.4 to form the cartridge body 20. Further, at the facing inner surfacesof the upper and lower halves 21 and 22, as shown in FIG. 6 and FIG. 7,disc walls forming the accommodating portion 25 and 26 are projected soas to be inscribed by the rising circumferential walls 23 and 24 whichstretch substantially rectangular overall. These disc walls forming theaccommodating portion 25 and 26 constitute the disc accommodatingportion 27 for accommodating the optical disc 4 in the cartridge body 20so that it freely rotates when mating and joining the upper and lowerhalves 21 and 22 to constitute the cartridge body 20. Note that, thedisc walls forming the accommodating portion 25 and 26 formed at theupper and lower halves 21 and 22 are constituted as shown in FIG. 6 andFIG. 7 by a plurality of rising walls of an arc shape formed positionedon the same circumference inscribed by the rising circumferential wall23 and the rising circumferential wall 24, respectively.

Further, in the lower half 22, as shown in FIG. 7, a circular centralopening 30 into which the disc table of the disc rotating mechanismarranged on the recording and reproducing apparatus side enters isprovided positioned at schematically a center thereof. In this centralopening 30, the hub 10 and the circumferential edge of the optical disc4 accommodated in the cartridge body 20 are made to face outward. Whenloading the disc cartridge 1 in the recording and reproducing apparatus,the disc table enters via the central opening 30, and the optical disc 4is placed on this disc table. At this time, the hub 10 is attracted bythe magnet arranged on the disc table, whereby the optical disc 4 ischacked on the disc table and becomes able to rotate integrally withthis disc table.

On the other hand, at schematically a center of the inner surface of theupper half 21, as shown in FIG. 6, a disc supporting portion 32 forsupporting the circumferential edge of the center hole 4 b of theoptical disc 4 accommodated in the cartridge body 20 is projected. Thisdisc supporting portion 32 is provided at a position facing the centralopening 30 provided in the lower half 22 when mating and joining theupper and lower halves 21 and 22 to constitute the cartridge body 20 andis formed in a ring of a size that can support the non-signal recordingportion provided at the inner circumferential side of the data signalrecording portion of the optical disc 4, that is, the circumferentialedge of the center hole 4 b. Namely, the disc supporting portion 32supports the non-signal recording portion of the optical disc 4 so thatthe signal recording portion does not come into direct contact with thecartridge body 20 when an outer disturbance is added to the disccartridge 1 and the optical disc 4 is moved in the cartridge body 20.

Further, in the upper half 21 constituting the upper surface of thecartridge body 20 and the lower half 22 constituting the lower surfaceof the cartridge body, as shown in FIG. 5, FIG. 6 and FIG. 7, openings33 and 34 for the recording and reproduction making at least one part ofthe data signal recording portion of the optical disc 4 rotatablyaccommodated in the disc accommodating portion 27 face outward over theinner and outer circumferences are respectively made facing each other.These openings 33 and 34 are positioned at the center of the cartridgebody 2 in the horizontal direction as shown in FIG. 3 and FIG. 4 and areformed so as to exhibit a rectangular shape over an area from a positionclose to the central opening 30 formed at the center of the lower half22 and the disc supporting portion 32 formed at the center of the upperhalf 21 to the front side of the cartridge body 20.

Further, at the front side of the upper half 21 and the lower half 22,as shown in FIG. 5, there are formed concave portions 37 and 38constituting the shutter member movement portion 35 for movement of theshutter member 8 moveably attached to the cartridge body 20 for openingor closing the openings 33 and 34 for recording and reproductionprovided in the cartridge body 20. These concave portions 37 and 38 areformed over the range of movement of the shutter member 35 as shown inFIG. 6 and FIG. 7 and are formed at the centers of the upper and lowerhalves 21 and 22 away from the two ends.

Note that the shutter opening operation member provided on the recordingand reproducing apparatus side enters into the shutter member movementportion 35 formed on the front side of the cartridge body 20 bycombining the concave portions 37 and 38 of the upper and lower halves21 and 22.

As shown in FIG. 6 and FIG. 7, projections 39 a and 39 b and 40 a and 40b are formed at the two ends of the front sides of the upper half 21 andthe lower half 22 by forming the concave portions 37 and 38 at thecenters.

Further, the front side at the openings 33 and 34 for recording andreproduction formed in the upper half 21 and lower half 22 is closed bythe connection pieces 41 and 42 as shown in FIG. 6 and FIG. 7. Theseconnection pieces 41 and 42 are formed while being biased to the matingsurface side so as to form a step portion on the outer surface of theupper and lower halves 21 and 22 as shown in FIG. 5. The connectionpieces 41 and 42 are mated with each other when the upper and lowerhalves 21 and 22 are mated and joined, are positioned at the center ofthe direction of thickness of the cartridge body 20, and constitute thethin portion 43 having a thickness less than that of the cartridge body20. The two sides of the thin portion 43 constituted positioned at thefront side of the openings 33 and 34 for recording and reproduction areused as the portion to and from which the optical pick-up and magnetichead constituting the recording and reproduction means arranged on therecording and reproducing apparatus side advance or retract. By formingthis as a thin portion 43 to and from which the optical pick-up andmagnetic head advance or retract, it becomes possible to reduce theamount of movement of the optical pick-u and magnetic head with respectto the disc cartridge 1 in the vertical direction and make it face orbring it into sliding contact with the optical disc 4.

Note that, the surfaces 41 a and 42 a of the inward side of theconnection pieces 41 and 42 are formed as arcs corresponding to theouter circumferential edge of the optical disc 4 accommodated in thecartridge body 20 as shown in FIG. 6 and FIG. 7.

At the two sides of the cartridge body 20, as shown in FIG. 3 and FIG.4, there are provided recess portions, 44 and 45 for preventingerroneous loading positioned at the lower half 22 side from the frontside toward the middle toward the back side with which the mechanism forpreventing erroneous loading provided at the recording and reproducingapparatus side engages. These recess portions 44 and 45 are formed bycutting the two sides of the lower half 22 as shown in FIG. 7. Theportions of the upper half 21, which is mated and joined to the lowerhalf 22 to constitute the cartridge body 20, mating with the recessportions 44 and 45 are formed as projecting pieces 46 and 47 withoutrecessing as shown in FIG. 6. Accordingly, the recess portions 44 and 45for preventing the erroneous loading provided in the cartridge body 20are formed as grooves having an L-shaped cross-section opening a portionover an area from the side surface to the lower surface of the cartridgebody 20. Here, the recess portions 44 and 45 for preventing theerroneous loading formed on the two sides of the cartridge body 20 areformed with a common length. Further, the recess portions 44 and 45 areprovided with concave engagement portions 44 a and 45 a with which onepart of the cartridge loading mechanism provided on the recording andreproducing apparatus side is engaged.

By providing the mechanism for preventing erroneous loading in which therecess portions 44 and 45 as mentioned above are formed and providingengagement portions with which these recess portions 44 and 45 areengaged on the recording and reproducing apparatus side on which thisdisc cartridge 1 is loaded, it is possible to prevent the loading ofanother disc cartridge not provided with the recess portions 44 and 45in the recording and reproducing apparatus in which the disc cartridge 1according to the present invention is to be loaded.

Further, between the upper half 21 and lower half 22 which are to bemated and joined with each other are provided a first positioningmechanism for positioning the mating positions of the upper and lowerhalves 21 and 22 in a direction indicated by an arrow X in FIG. 3, thatis, a direction parallel to the direction of movement of the shuttermember 8, and a second positioning mechanism for positioning the matingpositions in a direction indicated by an arrow Y in FIG. 3, that is, thedirection orthogonal to the direction of movement of the shutter member8, when mating and connecting these upper and lower halves 21 and 22.The first and second positioning mechanisms are provided positioned atthe corners on the two sides of the back side facing the front side ofthe cartridge body 20 to which the shutter member 8 is attached. Namely,the first and second positioning mechanisms are provided positioned in aregion surrounded by the disc accommodating portion 27 andcircumferential side wall 2 constituted in the cartridge body 20.

The first positioning mechanism for positioning the mating positions ofthe upper and lower halves 21 and 22 in the direction indicated by thearrow X in FIG. 3 is constituted by a pair of first and secondcylindrical bodies 48 and 49 which are engaged with each other providedat opposite positions of the upper and lower halves 21 and 22. Here, thefirst cylindrical body 48 projected at the upper half 21 side is formedso as to have an inner diameter large enough to accommodate the secondcylindrical body 49 projected at the lower half half 22 side. By fittingthese first and second cylindrical bodies 48 and 49 with each other,when the upper and lower halves 21 and 22 are mated with each other, themating positions in the direction indicated by the arrow X in FIG. 3,that is, the direction parallel to the direction of movement of theshutter member 8, are determined.

Further, the second positioning mechanism for positioning the matingpositions of the upper and lower halves 21 and 22 in the directionindicated by the arrow Y in FIG. 3 is constituted by a cylindricalportion 50 exhibiting a long oval shape projected at the lower half 22side as shown in FIG. 7 and a pair of parallel projections 51, 51projected at the upper half 21 side to fit over the two sides of thecylindrical portion 50 as shown in FIG. 6. The cylindrical portion 50projected at the lower half 22 side is formed in a long oval shapehaving surfaces 50 a and 50 b facing to each other parallel to thedirection of movement of the shutter member 8, and a pair of parallelprojections 51 and 51 projected at the upper half 21 side are formed inparallel to the direction of movement of the shutter member 8. Byfitting the cylindrical portion 50 having the surfaces 50 a and 50 bparallel to the direction of movement of the shutter member 8 betweenthe pair of parallel projections 51 and 51 parallel to the direction ofmovement of the shutter member 8, the mating positions of the matingupper and lower halves 21 and 22 in the direction indicated by the arrowY in FIG. 3 are determined by the pair of parallel projections 51 and 51and the parallel surfaces 50 a and 50 b of the cylindrical portion 50.

The holes of the second cylindrical body 49 provided in the lower half22 side and the cylindrical portion 50 of the long oval shapeconstituting the first and second positioning mechanisms arecommunicated with the outer surface of the lower half 22. Whenassembling the disc cartridge 1, they are used as the positioning holes52 and 53 with which the positioning pins arranged on the recording andreproducing apparatus side are engaged.

On the facing inner surfaces of the upper half 21 and lower half 22constituting the cartridge body 20 by this mating and connection, asshown in FIG. 6 and FIG. 7, pairs of mating projections 71 to 92constituting the fusing portions are integrally projected at a pluralityof positions. These mating projections 71 to 92 are formed incylindrical shapes having schematically the same diameter, but themating projections provided at the upper half 21 are formed with smallerheights than the mating projections provided at the lower half 22. Notethat, these mating projections 71 to 92 are formed so that the overallheights in axial direction are substantially equal to the height of therising circumferential walls 23 and 24 mated with each other when thetwo halves are mated.

Here, concretely explaining the positions at which the matingprojections 71 to 92 provided at the upper half 21 and lower half 22 areformed, the mating projections 71 to 92 are provided in the regionsurrounded by the rising circumferential walls 23 and 24 constitutingthe circumferential side wall 2 of the cartridge body 20 and the wallsforming the disc accommodating portion 25 and 26 constituting the discaccommodating portion 27 as shown in FIG. 6 and FIG. 7.

In the region surrounded by the rising circumferential walls 23 and 24constituted at one corner at the front side of the upper half 21 andlower half 22 and the walls forming the disc accommodating portion 25and 26, a pair of mating projections 71 and 72 are provided. The regionof one corner of the front side of the upper half 21 and lower half 22is used as the region in which a coil spring for biasing the shuttermember 8 is to be arranged as will be mentioned later, so the matingprojections 28 and 29 are provided positioned at the back side of theupper half 21 and lower half 22 in which the rising circumferentialwalls 23 and 24 and the walls forming the disc accommodating portion 25and 26 are in close contact with each other as shown in FIG. 6 and FIG.7. The positions at which these mating projections 71 and 72 areprovided are the positions on the two sides at which the recess portions44 and 45 for preventing the erroneous loading constituted in thecartridge body 20 are formed as shown in FIG. 7.

Further, in the region surrounded by the rising circumferential walls 23and 24 and the walls forming the disc accommodating portion 25 and 26constituted on one corner of the front side of the upper half 21 andlower half 22, two pairs of disc cartridges 73 and 74 and 75 and 76 areprovided. One pair of mating projections 73 and 74 of the two pairs ofmating projections 73 and 74 and 75 and 76 is provided at the positionson the inward side of the upper half 21 and lower half 22 offset fromthe rising circumferential walls 23 and 24 to the walls forming the discaccommodating portion 25 and 26 side as shown in FIG. 6 and FIG. 7. Theother mating projections 75 and 76 are provided at positions at the backside of the upper half 21 and lower half 22 at which the risingcircumferential walls 23 and 24 and the walls forming the discaccommodating portion 25 and 26 approach each other and at the two sideswhere the recess portions 44 and 45 for preventing the erroneous loadingare formed.

Further, in the region of the projections 39 a and 39 b and 40 a and 40b projected at the two sides of the front side of the upper half 21 andlower half 22, pairs of projections 77 and 78 and 79 and 80 are formed.

In the region surrounded by the rising circumferential walls 23 and 24and the walls forming the disc accommodating portion 25 and 26constituted on each corner of the back sides of the upper half 21 andlower half 22, three pairs each of mating projections 81 and 82; 83 and84; and 85 and 86 and 87 and 88; 89 and 90; and 91 and 92 are provided.Each pair of mating projections 81 and 82 and 89 and 90 in each regionis provided positioned at each corner on the back side of the upper half21 and lower half 22 as shown in FIG. 6 and FIG. 7, while each otherpair of mating projections 83 and 84 and 87 and 88 is provided at aposition at the back side at which the rising circumferential walls 23and 24 and the walls forming the disc accommodating portion 25 and 26approach each other. Further, the pair of mating projections 85 and 86provided in the region on one corner of the back side of the upper half21 and lower half 22 is provided at a position close to a pair ofparallel projections 51 and 51 and cylindrical portion 50 constitutingthe second positioning mechanism. Furthermore, the pair of matingprojections 91 and 92 provided in the region of one corner of the backside of the upper half 21 and lower half 22 is provided close to thefirst and second cylindrical bodies 48 and 49 constituting the firstpositioning mechanism.

The mating projections 71, 73, 75, 77, 79, 81, 83, 85, 87, 89 and 91formed on the upper half 21 are formed in cylindrical shapes with flatend surfaces 60 on the mating surfaces surface side as shown in FIG. 8and FIG. 9.

On the other hand, among the mating projections formed on the lower half22, the end surfaces 61 of the mating surface side of the matingprojections 72 and 76 which are in the regions surrounded by the risingcircumferential wall 24 and the walls forming the disc accommodatingportion 26 constituted at the corners of the front side and which areprovided on the two sides where the recess portions 44 and 45 forpreventing erroneous loading positioned at the back side at which therising circumferential wall 24 and the walls forming the discaccommodating portion 25 approach each other are former, as shown inFIG. 8 and FIG. 9, projections 62 for fusing are formed exhibiting asemi-arc shape and with a thickness narrower toward the tip end. At thistime, the projections 62 are formed at positions on the risingcircumferential wall 24 side.

Further, on the end surfaces 61 of the mating projections 86 and 92provided in the vicinity of the cylindrical portion 50 and the secondcylindrical body 49 constituting the first and second positioningmechanisms formed on the lower half 22 as shown in FIG. 10 and FIG. 11are formed projections 62 for fusing exhibiting a semi-arc shape andhaving a thickness narrower toward the tip end. At this time, theprojections 62 are formed along the end surfaces 61 opposite to thecylindrical portion 50 and the second cylindrical body 49.

On the other hand, the end surfaces 61 of the mating surface side of theother mating projections 78, 80, 82, 84, 88, and 90 provided on thelower half 22, as shown in FIG. 12 and FIG. 13, are formed withprojections 63 for fusing formed in ring shapes which continuesuccessively over the entire circumference of the end surfaces 61. Theseprojections 63 also have a thickness which becomes smaller toward thetip ends.

Here, the reason why the projections 62 to be formed on the end surfaces61 of the mating projections 72 and 76 provided in the vicinity of theposition at which the mating rising circumferential walls 23 and 24 andthe walls forming the disc accommodating portion 25 and 26 approach eachother and the mating projections 86 and 92 provided in the vicinity ofthe cylindrical portion 50 and the second cylindrical body 49constituting the first and second positioning mechanisms to be mated andjoined to each other are formed in the semi-arc shape is so that, whenthe ultrasonic wave is applied, the portions of these mating projections72 and 76 and 86 and 92 will not vibrate much in comparison with theportions of the other mating projections 78, 80, 82, 84, 88 and 90.Namely, vibration is inhibited due to the fact that portions where theupper and lower halves 21 and 22 mate and engage such as the first andsecond positioning mechanisms exist nearby, so sufficient vibration isnot generated. Therefore, so as to enable sufficient melting even by alittle vibration, the projections 62 to be provided at the matingprojections 72 and 76 and 86 and 92 are formed in the semi-arc so as toreduce the amount of the melting. These projections 62 are desirablyprovided at positions of the upper and lower halves 21 and 22 which arefarthest from the mating and engaging portions as mucky as possible sothat they can sufficiently vibrate by the application of the ultrasonicwaves. For this reason, the projections 62 to be provided at the matingprojections 72 and 76 and 86 and 92 are provided at positions away fromthe mating portions of the upper and lower halves 21 and 22 as mentionedabove. Note that, it is sufficient so far as the projections 62 to beprovided at the mating projections 72 and 76 and 86 and 92 are formed sothat they can be reliably melted with little vibration and can beconstituted by a plurality of fine projections-provided on the endsurfaces 61 too.

So as to mate and join the upper half 21 and lower half 22 constitutedas mentioned above to assemble the cartridge body 20, the first andsecond cylindrical bodies 48 and 49 constituting the first positioningmechanism are fitted with each other and, at the same time, thecylindrical portion 50 exhibiting the long oval shape is fitted betweenthe pair of parallel projections 51 and 51 constituting the secondpositioning mechanism so that the upper and lower halves 21 and 22 aremated to each other. By mating them in this way, the upper half 21 andlower half 22 are combined while positioned in the direction indicatedby the arrow X in FIG. 3 and the direction indicated by the arrow Y inFIG. 3, that is, in directions orthogonal to each other. At this time,the mating projections 71 to 92 provided at the upper and lower halves21 and 22 are mated to each other and further also the risingcircumferential walls 23 and 24 and the walls forming the discaccommodating portion 25 and 26 are mated to each other.

As mentioned above, the upper and lower halves 21 and 22 are placed onan ultrasonic welding device in a state assembled with each other, thephone for applying an ultrasonic wave to the upper half 21 is pressedagainst them, and the ultrasonic wave is applied. When the ultrasonicwave is applied, it concentrates at the projections 62 and 63 formed onthe end surfaces 60 and 61 of the mating projections 71 to 92 which aremade to abut against each other and so these projections 62 and 63 andthe circumferential edges thereof are vibrated by the ultrasonic wave.By this ultrasonic vibration, the projections 62 and 63 generate heatand melt. When the application of the ultrasonic wave is suspended, themolten plastic of the mating projections 62 and 63 resolidify to fusetogther the end surfaces 60 and 61 of the mating projections 71 to 92.

As mentioned above, the shape of the projections 62 and 63 is selectedso the projections 62 and 63 are substantially uniformly melted inconsideration of the fact that the state of vibration when theultrasonic wave is applied differs depending upon the position at whichthe mating projections 71 to 92 are provided. Accordingly, since it ispossible to melt the projections 62 and 63 in a short time and fusetogether the mating projections 71 to 92, it is possible to prevente thephone of the ultrasonic welding device from being kept in contact withthe outer surface of the upper half 21 for a long time and thus possibleto prevented the fine pebbling applied to the surface of the upper half21 from being damaged and smoothed.

Further, by shortening the time of application of the ultrasonic wave,it is possible to prevent the problem of the optical disc 4 accommodatedin the cartridge body 20 vigorously vibrating in the disc accommodatingportion 27 and the surfaces rubbing together to cause the walls formingthe disc accommodating portion 25 and 26 to be shaved and shaving powdergenerated and adhering to the surface of the optical disc 4.

Further, since-the fusing is carried out at the corners on the frontside and back side of the upper half 21 and lower half 22, the halvesare reliably joined. Particularly, in the cartridge body 20 of thepresent embodiment, the two sides at which the recess portions 44 and 45for preventing erroneous loading are fused together, so even if theerroneous loading preventing members on the recording and reproducingapparatus side which were supposed to engage are engaged with theserecess portions 44 and 45 with a force trying to push open the upper andlower halves 21 and 22, the upper and lower halves 21 and 22 will noteasily separate and the joined state will be reliably maintained.

As mentioned above, the cartridge body 20 constituted by joining theupper half 21 and lower half 22 by the ultrasonic welding, as shown inFIG. 3 and FIG. 4, has attached to it a shutter member 8 for opening andclosing the openings 33 and 34 for recording and reproduction. Thisshutter member 8 is provided for the purpose of closing the openings 33and 34 as shown in FIG. 3 and FIG. 4 at the non-use state when the disccartridge 1 is not loaded in the recording and reproducing apparatus soas to prevent dust etc. from entering into the cartridge body 20 andbeing adhered to the surface of the optical disc 4 via these openings 33and 34 and thereby protect the optical disc 4.

This shutter member 8 is formed by pressing a thin metal plate and, asshown in FIG. 5, comprises a first shutter portion 55 and a secondshutter portion 56 having outer shapes large enough to close theopenings 33 and 34 for recording and reproduction, respectively, and aconnection piece 57 joining the base end portions of these first shutterportion 55 and second shutter portion 56, and is formed in substantiallya squared U-shape as a whole. The first shutter portion 55 is formed ina rectangular shape slightly long in the front and back direction andhaving a size large enough to open or close the opening 33 for therecording and reproduction on the upper half 21. Further, the secondshutter portion 56 is formed with a size large enough to close thecentral opening 30 together with the opening 34 for recording andreproduction on the lower half 22 and is formed in a rectangular shapefurther longer in the front and back direction than the first shutterportion 55. The front end of this second shutter portion 56 is supportedby the shutter holding plate 58 which is attached to the main surface ofthe outward side of the lower half 22 and which prevents the secondshutter portion 56 from floating up from the lower half 22. Further, theconnection piece 57 of the shutter member 8 is formed so as to have aheight substantially equal to the thickness of the front surface of thecartridge body 20.

In the shutter member 8, a slide member 58 is attached to the insidesurface of this connection piece 57, and the shutter member 8 isattached to the cartridge body 20 via this slide member 58. This slidemember 58 is a member shaped in substantially a rod-like shape by aplastic material as shown in FIG. 5 and has a length substantially twicethe width of the connection piece 57 of the shutter member 8. In theslide member 58, portions 59 a and 59 b for engagement with thecartridge body 20 are provided at the two ends. By an engagement ofthese engagement portions 59 a and 59 b in the slide guide groove formedin the shutter member movement portion 35 constituted on the frontsurface of the cartridge body 20, the slide member 58 moves along theslide guide groove. By the movement of the slide member 58 along theslide guide groove, the shutter member 8 attached to this slide member58 is moved in a direction opening and closing the openings 33 and 34for recording and reproduction.

The shutter member 8 is constantly biased in a direction closing theopenings 33 and 34 for the recording and reproduction by the coil spring54 arranged in the cartridge body 20. The coil spring 54 is arranged inthe region surrounded by the circumferential side wall 2 and the discaccommodating portion 27 constituted at one corner at the front side ofthe cartridge body 20 in a state with the two end portions arecompressed and the elastic force given. It is arranged in the cartridgebody 20 by engaging a tip of one arm with the slide member 58 and, atthe same time, engaging the tip of the other arm with the matingprojection 72 provided at the lower half 22.

On the main surface of the outward side of the upper half 21 and lowerhalf 22 of the cartridge body 20, as shown in FIG. 3 and FIG. 4, concaveportions 64 and 65 for the shutter slide having almost equal depths asthe plate thickness of the first shutter portion 55 and the secondshutter portion 56 are provided over an area from the region coveringthe circumferential edges of the opening 33 for recording andreproduction and the opening 34 for recording and reproduction in whichthe first shutter portion 55 and the second shutter portion 56 of theshutter member 8 move to a region of the front side of the cartridgebody 20. These concave portions 64 and 65 enable the installation of theshutter member 8 so that the first shutter portion 55 and the secondshutter portion 56 thereof are on the same plane as the outer surface ofthe cartridge body 20. Accordingly, the thickness dimension of the disccartridge 1 is not increased even if the shutter member 8 is installedin the cartridge body 20.

The disc cartridge 1 is provided with a mechanism for preventingerroneous recording which prevents erroneous erasing of the data signalrecorded on the optical disc 4. This mechanism for preventing erroneousrecording is constituted as shown in FIG. 5 by an erroneous recordingpreventing member 66 which is arranged at a position at one corner ofthe back side corresponding to the one corner of the front side in whichthe coil spring 54 of the lower half 22 is arranged and by an erroneousrecording detection hole 67 provided in the upper half 21.

The erroneous recording preventing member 66 is moved along the guidehole 68 provided in the lower half 22. At the same time, an operatingportion faces the operating opening 69 formed by cutting one part of therising circumferential wall 23 and rising circumferential wall 24 of theback side of the upper half 21 and lower half 22. The erroneousrecording preventing member 66 operates the operating portion from theoperating opening 69 to switch between the first position for closingthe erroneous recording detection hole 67 and the second position foropening this erroneous recording detection hole 67. The erroneousrecording preventing member 66, when set at the first position forclosing the erroneous recording detection hole 67, prevents the entry ofthe erroneous recording detection means provided on the recording andreproducing apparatus side into the erroneous recording detection hole67 and makes recording of the data signal with respect to the opticaldisc 4 possible. Further, when set at the second position for openingthe erroneous recording detection hole 67, the erroneous recordingpreventing member 66 allows the entry of the erroneous recordingdetection means provided on the recording and reproducing apparatus sideinto the erroneous recording detection hole 67 and makes recording ofthe data signal with respect to the optical disc 4 impossible.

When the disc cartridge 1 constituted as mentioned above is insertedinto the cartridge loading portion of the recording and reproducingapparatus, the shutter member 8 is moved to the position for opening theopenings 33 and 34 for recording and reproduction by the shutter openingmember on the recording and reproducing apparatus side. At this time,also the central opening 30 is opened.

Further, when the disc cartridge 1 is inserted into the cartridgeloading portion of the recording and reproducing apparatus, the disctable on the recording and reproducing apparatus side enters from thecentral opening 30 into the internal portion. On this disc table isprovided a magnet. The hub 10 of the optical disc 4 is attracted in astate where the disc table enters from the central opening 30 to theinternal portion of the disc cartridge 1, thereby to perform magnetchacking of the optical disc 4. Further, the disc table is attached tothe spindle shaft driven to rotate by the spindle motor. This spindleshaft is inserted into a spindle shaft insertion hole 12 formed in thehub 10 of the optical disc 4 chacked on the disc table.

In the disc cartridge 1, the optical pick-up on the recording andreproducing apparatus side is positioned in the opening 4 for recordingand reproduction of the lower half 22 side opened when the shuttermember 8 performs the sliding operation corresponding to this. At thesame time, an external magnetic field generating device is positioned inthe opening 3 for the recording and reproduction on the upper half 21side corresponding to this. The recording operation or the reproductionoperation is carried out to or from the disc cartridge 1 atthe-recording and reproducing apparatus side, whereby when the spindlemotor is activated and the spindle shaft is driven, the optical disc 4is driven to rotate at a high speed.

The optical pick-up emits a laser beam to the data signal recordingportion of the optical disc 4 which is being driven to rotate andperforms processing for the reproduction of the data signal recorded onthis data signal recording portion by a well known reproduction process.Further, the external magnetic field generation device performsprocessing for recording a desired data signal in this data signalrecording portion by a well known recording process in a state where thelaser beam emitted from the optical pick-up is emitted to the datasignal recording portion of the optical disc 4.

Further, while the above-mentioned disc cartridge 1 accommodated anoptical disc 4 which enabled the recording and reproduction of a datasignal, it is also possible to accommodate an optical disc used only forreproduction. In the disc cartridge 1 accommodating an optical disc usedonly for reproduction, the opening for recording and reproduction whichis provided on the upper half 21 side becomes unnecessary and that sideis closed.

Further, the recording medium accommodated in the cartridge body 20 isnot restricted to an optical disc and can be any medium so far as it isa disk-like recording medium in which a data signal is recorded, forexample, a magnetic disc.

Next, another embodiment of the disc cartridge 2 according to thepresentinvention will be explained by referring to FIG. 14, FIG. 15, andFIG. 16. This disc cartridge 2 has a principal portion of the sameconfiguration as that of the disc cartridge 1, so the same referencenumerals will be given to common portions and detailed explanations willbe omitted. An explanation is made only by explaining the differentportions.

This disc cartridge 2 has a different structure of the matingprojections 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, and 92 provided onthe lower half 22 as shown in FIG. 14. Namely, it has a differentstructure for the projections 93 for fusing to be formed on the endsurfaces 61 of the mating projections 72, 74, 76, 78, 80, 82, 84, 86,88, 90, and 92. Further concretely explaining one of these matingprojections by referring to FIG. 15 and FIG. 16, a projection 93 forfusing exhibiting a discontinuous annular shape comprising the first arcprojection 93 a and the second arc projection, 93 b having lengthscovering substantially half the circumference of the end surface 61 andformed so as to face each other is provided on the end surface 61 ofthis mating projection 72.

The first and second arc projections 93 a and 93 b constituting thisprojection 93 are formed as small projections in which, as shown in FIG.16, the cross-section of the portion with the end surface 61 side as abottom and the top edge as the top point is given substantially atriangular shape.

According to the above disc cartridge 2, due to the formation of theprojections 93 for fusing which exhibit the discontinuous annular shape,which can be melted in a short time for joining and fixing the halvesand, at the same time, form strong joins, on the end surfaces 61 of themating projections 72, 74, 76, 78,-,80, 82, 84, 86, 88, 90, and 92provided in the lower half 22, it is possible to shorten the time forthe ultrasonic welding and reduce the amount of the electric powerconsumed.

Further, various combinations of the mating projections 72, 74, 76, 78,80, 82, 84, 86, 88, 90, and 92 provided in the lower half 22 may beadopted in accordance with the positions of arrangement.

In the disc cartridge 3 of the present embodiment, the projections 94for fusing to be formed on the end surfaces 61 of the mating projections82 and 90 provided at positions close to the corners among the matingprojections 82, 84, 86, and 88, 90, and 92 arranged in the regionssurrounded by the rising circumferential walls 23 and 24 and the wallsforming the disc accommodating portion 25 and 26 constituted at the twocorners of the back side of the lower half 22 are formed as shown inFIG. 17, FIG. 18, and FIG. 19. The projections 94 for fusing are formedin a discontinuous annular shape by forming the first projection 93 a inthe form of an arc and the second projection 93 b in the form o-f an arcso as to face each other. The projections 94 are also formed as smallprojections having a thickness smaller toward the tips with asubstantially triangular cross-section of the portion with the endsurface 61 side as the bottom and the top edge as the top point as shownin FIG. 18.

Further, the projections 95 for fusing formed on the end surfaces 61 ofthe mating projections 84 and 88 provided at the positions at which therising circumferential walls 23 and 24 and the walls forming the discaccommodating portion 25 and 26 on the accommodated in the cartridgebody is achieved. Further, since the application time of the ultrasonicwave can be made short, it is possible to prevent the damage of thecartridge body and further the damage of the disk-like recording mediumaccommodated in the cartridge body.

1. A disc cartridge comprising: a disc recording medium in which a datasignal is recorded; a cartridge body exhibiting a rectangular shapeformed by mating and joining upper and lower halves at circumferentialedges of which are formed rising circumferential walls which are matedto each other to constitute circumferential side walls and accommodatingportion walls which are mated to each other at mating inner surfaces toconstitute a recording medium accommodating portion in which the discrecording medium is accommodated, the circumferential side wallsconnecting with the accommodating portion walls in a connecting area; anopening for recording and reproduction which is formed in upper andlower surfaces of the cartridge body over an area from the vicinity ofthe center of the cartridge body to a front side of the cartridge body;a shutter member which is provided with a shutter portion for opening orclosing the opening and which is attached to the cartridge body so thatit can move along a front surface of the cartridge body; recess portionsfor preventing erroneous loading formed on both sides of the cartridgebody on the lower half from the front side to the middle toward the backside; and a plurality of fusing portions for mating and fusing togetherthe upper and lower halves at facing surfaces of said upper and lowerhalves, wherein each of said fusing portions is provided with a matingprojection cylindrically formed at one of said upper and lower halvesand a mating projection cylindrically formed at another of said upperand lower halves; wherein the mating projections formed at said anotherof said upper and lower halves include a flat annular end surface, andthe mating projections formed at said one of said upper and lower halvesinclude an annular end surface to be connected to said flat annular endsurface and a projection which has a semicircular shape along a part ofsaid annular end surface and which is formed on said annular end surfaceon said rising circumferential wall side to be fused together with saidflat annular end surface to connect the upper and lower halves, whereinsaid mating projections including said semicircular shaped projectionsare provided at positions adjacent to where said rising circumferentialwalls and said walls forming said recording medium accommodating portionintersect and one of said fusing portions for mating and fusing saidupper and lower halves is provided at a thin portion having a thicknessless than that of said cartridge body formed by mating of said upper andlower halves at a front side of said opening formed in said cartridgebody and at substantially a center of said cartridge body and anotherplurality of said mating projections including complete annular shapedprojections are formed at one of said upper and lower halves atpositions corresponding to the corners of the cartridge body, wherein atleast one pair of fusing portions is provided positioned at the twosides of said cartridge body at which said recess portions are formed.